Montag, 22. April 2013, 16:30 - 17:30 iCal
Laboratory and Field Investigations of the Aquatic Toxicity of Metal Mixtures
Aktuelle Themen in den Umweltgeowissenschaften II
Fakultät für Geowissenschaften, Geographie und Astronomie, Geozentrum, Eberhard Clar-Saal (2B 204)
Althanstrasse 14, UZA 2, 1090 Wien
Seminar, Workshop, Kurs
Concentrations of metals showing toxic effects to aquatic species (Zn, Cu, Cd, Ni) are influenced by natural and anthropogenic processes. Major anthropogenic sources of metals into natural water systems include mining wastes, sewage treatment plants, waste incinerators and power plants. Effluents from abandoned metal sulfide mines impact the site under investigation, namely the North Fork of Clear Creek, Colorado. Rarely is only one toxic metal present in these systems, leading to mixture toxicity that is currently difficult to predict. As part of a project to provide mixture-toxicity data for development of multi-metal toxicity models, we tested the toxicity of binary mixtures of Cu, Zn, Cd, and Ni. To analyze the interactions of these metals, we exposed Daphnia magna neonates to the metals alone and in binary combinations in standard 48-h toxicity tests conducted in USEPA moderately hard reconstituted lab water to which 6 mg/L of Suwannee River fulvic acid was added. For each combination of metals in the binary mixtures, one metal was held constant at a specified concentration while the second metal was varied through a series that ranged from nonlethal to lethal concentrations; then the roles of the two metals were reversed in a separate series of tests. The talk will highlight work with the Ni:Cu and Ni:Cd systems, where sub-lethal concentrations of nickel protected against the toxicity of cadmium, with mortality only occurring at considerably higher cadmium concentrations than in paired cadmium-only tests (i.e., less-than-additive toxicity). In contrast, a synergistic (i.e. greater-than-additive) toxicity occurred in binary mixtures of copper and nickel, with mortality occurring at concentrations of each of the two metals that were non-lethal in the paired single-metal tests. These findings provide evidence for the dominance of competition of metals for complexation to biological ligands or to dissolved organic matter, depending on the metal combination in question. Seasonal variations in stream hydrology provide a range of water compositions that allow us to examine the relationship between the laboratory findings and what is observed for the field situation.
Veranstalter
Dr. James Ranville, Colorado School of Mines, USA
Kontakt
Vesna Micic Batka
Department of Environmental Geosciences
Environmental Geosciences Group
01/427753372
vesna.micic@univie.ac.at
Erstellt am Mittwoch, 20. März 2013, 07:10
Letzte Änderung am Donnerstag, 18. April 2013, 09:31